I am not sure that this is helpful, but if it was working on the test bench after you test wired everything than you cave connected something wrong for the real installation. Disconnect the motor couplers so that no screw will move if the stepper motors starts rotating to avoid hitting the limits. Disconnect all the motors except one and test one axis at a time. Before doing that, check that the DIR pin is changing level when you issue a direction command, for example G0 X100 first and to change direction issue G0 X0. Start with one axis fix that axis first. Regarding the slaving, how did you slave the Y? Did you connect the control signals in parallel to each driver or did you connect the two motors in parallel? In 3D printers it is very common to connect stepper motors in parallel to one driver but that is totally wrong. Each stepper MUST have it's own driver and the only thing which you can connect in parallel are the control signals from the Arduino to the drivers. Anyway, if I was slaving your kit then I'd have one PSU for the two slaved motors and one for X and Z. If the PSUs are made for both 120V and 240V then it does not matter if you connect them to 120VAC or 240VAC as long as you flip the switch on the PSU.
Regarding the kit you have, it seems to be a nice one. I am also using DQ542MA drivers and they have been very reliable, never failed on me, except once, which was caused by my own stupidity. In my case I happened to cause a short circuit between two terminals but the same can happen if motors are disconnected under power. Don't EVER disconnect a stepper with the power on because it will fry your driver. If you have done this then don't worry, there is a fuse in each driver which is pretty easy to repair. Here is how I repaired mine:
The other thing which can cause the symptom is that the limit switches are not connected or are defined wrong. My Arduino based 3D printer uses one limit switch on each axis and if the switch is not connected then the motors can only move in one direction, only positive moves are allowed. I don't know how familiar you are with the firmware and hos your firmware behaves. I have no idea about UGS. My CNC is using UCCNC and UC300ETH, I am using Arduino and Marlin firmware in my 3D printers only.